Targeting plot for a paired-comparison design

The paired-comparison counterpart of a test-information display. Every object is a dot at its location (x) and its design information (y, the pooled Fisher information of the comparisons it took part in), the dot sized by how many comparisons that is. A reference curve, read on the right axis, traces the information a single new comparison would carry against an opponent at each location – anchored at the centre of the scale, so it peaks at gap zero and falls away with the gap. The curve is the visual explanation of why an adaptive design chases near-neighbour contests: information is bought most cheaply where the two objects are close, and a well-targeted design lifts the low dots by pairing their objects against opponents near them.

Usage

plot_btl_targeting(fit, grid = NULL)

Arguments

fit

A paired-comparison fit from btl.

grid

Optional location grid for the reference curve.

Value

Called for its plotting side effect; invisibly NULL.

See also

btl_information, btl_next_pairs

Examples

set.seed(1)
beta <- c(A = -1, B = -0.3, C = 0.4, D = 0.9)
pr <- t(combn(names(beta), 2))
d <- data.frame(a = rep(pr[, 1], each = 30), b = rep(pr[, 2], each = 30))
d$win <- ifelse(runif(nrow(d)) < plogis(beta[d$a] - beta[d$b]), d$a, d$b)
plot_btl_targeting(btl(d, "a", "b", "win"))